One of the characteristics of tumor cells (cancer cells) is that as compared to normal cells, they undergo rapid cell division, resulting in a significantly high cell proliferation rate. Thus, many anticancer agents to kill tumor cells or to inhibit their proliferation are drugs that inhibit division of tumor cells (cancer cells). For example, alkylating agents are drugs that act on the DNA of tumor cells (cancer cells) to crosslink the bases between double strands, thereby inhibiting DNA replication and blocking cell division. Antimetabolites such as 5-FU, etc., are drugs that inhibit DNA synthesis and block cell division.
As for such a drug (anticancer agent) to inhibit rapid division of tumor cells (cancer cells), expectations are building for development of a drug formulated with a physiologically active peptide having a relatively small number of amino acid residues and a low molecular weight. As compared to anticancer drugs formulated with conventional chemical substances, drugs formulated with physiologically active peptides are expected to reduce side effects while they are also expected to act solely on specific target cells (cancer cells). For example, Patent Document 1 and Patent Document 2 disclose antitumor peptides (anticancer peptides) that are as short as 50 or fewer amino acid residues.